There's been a lot of apartment construction in the District in the last few years, but most of it is at the high end of the market. And that has led to a derth of more affordable housing.

The situation is evident in the rents tenants pay. Average rent for a high-end, "class A" apartments has fallen by 1 percent to $2,648 while the supply of such spaces has nearly doubled in the past four years, The Washington Post reported citing data from Delta Associates. Rents for more affordable "class B" apartments, meanwhile, are on the rise to an average of $1,917. And vacancy rates of those apartments are a low 3 percent.

In some sense, the market is a victim of its own success with developers embarking on more high-end projects at the behest of investors hoping to replicate prior success in areas like the 14th Street corridor, according to The Post. That is widening a gap between high-end apartments and more affordable market segments and reinforcing a longer-term trend. Between 2000 and 2010, the D.C. Fiscal Policy Institute says, the stock of apartments priced below $750 shrank by 50 percent while those priced over $1,500 grew threefold.